We are both landscape/garden designers and landscapers... A lot to plannin' gardens is what it is that you are trying to achieve... Since you have a blank canvas I would suggest that you work on the "bones" of what you want down the road and leave the little stuff alone for now... This means dealing with structure, composition, balance, shapes, textures, etc... If you are in full sun and desire some plants that don't like full sun that means trees... Some trees are not as good as others if you want to plant under them... Maples are hogs... Black walnut are poisonous... Red buds are hogs...
I would have to know what your temperature zone is and your light to begin to suggest trees/shrubs that might act well as your bones... Plus, if you are in the UK that might make it harder since I'm not too sure what you can get there... But willing to help the best we can...